From all that has been gathered, Both rad animals produced the same loot as zombies when killed. The bears gave better loot than the wolves.
Bears take 4 hits from a bolt action rifle and Wolves take 2.
The red animals were apparently placeholders for something else to be announced by the developers at a later date, however, nothing new was released before the closure of Legacy in 2015.
The developers decided to remove zombies because they did not wish that the game be considered a "Zombie Survival Game," or a DayZ clone. The removal of Zombies from Legacy was a matter of controversy among players.